Takefumi Ogawa

Tracking of user position and orientation by stereo measurement of infrared markers and orientation sensing

A real-time three-dimensional position and orientation tracking system is proposed for use with wearable augmented reality systems. The system combines infrared markers with a head-mounted stereo camera to detect the users position, and an orientation sensor to measure the orientation of the users head. An extended Kalman filter is employed to reduce triangulation and orientation error by integrating the signals acquired by multiple sensors. The system is evaluated through a series of experiments, and a navigation system implemented using the proposed scheme is presented. The accuracy of the system is shown to be sufficient to allow annotations and virtual objects to be overlaid on real scenes via a head-mounted display without confusion.

Tools for constructing pseudo-3D space on the WWW using images

Recently, due to advancements in virtual reality and computer graphics technologies, a virtual space that looks as real as a real space has been constructed. Accordingly, there are many studies that employ virtual spaces to support human communication and remote working. Until now, the virtual space employed by these studies has been composed of geometric models. Since the real space is very large and there are a lot of objects in the real world, the cost of modeling the real space is very high. In our previous paper,10) we proposed a method for building a virtual space using image data, named theimage based non-rendering (IBNR), in order to cut down the cost. In this paper, we explain the design and implementation of the tools which we implemented to construct virtual spaces based on IBNR. With these tools, it is easy to construct and renew a large-scaled virtual space based on the real space.

Interactive Reconfiguration Techniques of Reference Frame Hierarchy in the Multi-viewport Interface

This paper proposes interaction techniques for interactive reconfiguration of the transformation hierarchy among coordinate systems in the multi-viewport interface, which we have proposed for versatile three-dimensional (3-D) operations. The multi-viewport interface provides an arbitrary number of secondary views in window frames placed in a virtual environment, each showing the same or different virtual scenes from different perspectives. Using the multi-viewport interface, the user can seamlessly perform a variety of object manipulation and user navigation operations between multiple virtual scenes. The relationships among the reference frames of a window frame, the primary view outside the frame, the secondary view inside the frame, and the user define the characteristics and usability of a virtual environment; however, our former framework supports limited types of relationships and does not support interactive reconfiguration of the hierarchy. This paper extends our former framework with deeper analysis of combinations of the transformation hierarchy and a set of new interaction techniques for interactive reconfiguration of the hierarchy.

A hybrid image-based and model-based telepresence system using two-pass video projection onto a 3D scene model

A telepresence system is presented that has the advantage of both model-based and image-based approaches, namely, free viewpoint control and real-time color update with live video. A remote place is presented as a virtual environment by using live video projection captured by a head-worn camera onto the static 3D geometry. The observer can then observe the remote place in cooperation with the remote camera man, and give him a set of 3D instructions by a mouse.

A PDA-based See-through Interface within an Immersive Environment

This paper investigates the use of tangible user interfaces (TUIs)for controlling multimedia systems. It presents a preliminary study where a tangible device called ARemote is used to choose TV channels in a relatively large list by performing 3D gestures. Three different interaction strategies, that either relies on crossing or scrolling, have been developed and tested in a controlled experiment.With the use of an immersive display system such as the CAVE, the user is able to perceive a 3D environment realistically. However, the interaction on such systems faces inherent difficulties such as inaccurate tracking, lack of depth cues, and unstable spatial manipulation without the sense of touch. In this paper, we propose a see-through lens interface using a PDA (Personal Digital Assistant) for supporting spatial manipulation within an immersive display. Compared to related techniques, a PDA-based see-through lens interface includes the following advantages, which we believe will provide more natural and flexible manipulation and interaction schemes in an immersive environment: physical contact of the screen surface for easy 2D manipulation in 3D space, built-in controls for immediate command execution, and a built-in display for a flexible GUI (graphical user interface). This paper describes the basic ideas and implementation details of the proposed system and some functionalities provided with the interface, such as image-based selection of a 3D object.

Design and implementation of a communication support system based on projection of real space on virtual space

Virtual reality is the technology which enables us to feel as if we are in virtual space. On the other hand, mobile computing, which makes use of wireless network technologies, enables us to use computers anywhere in the world. The integration of these two technologies will make it possible for users to communicate with other persons separated at long distance, anywhere and anytime. Based on this idea, we have proposed a system called the invisible person environment. In this environment, events that occur in the real space will immediately be reflected onto virtual space and vice versa. Therefore, the environment gives users a rich communication functionality with so much presence that they may have the illusion that they are meeting in the same space. In this paper, we show our design and implementation of the invisible person system that facilitates the mappings of the real space onto virtual space. In this system, real-time video resources are effectively used to support communications.

Ja-Net on grid for adaptive resource distribution in grid environment

We propose a mobile agent system called Ja-Net on grid by which to simplify parallel application development in a grid environment. The Ja-Net on grid system is built on the Ja-Net architecture and enables application programmers to write programs that run efficiently in a grid environment by agents doing collaborative activities among agents based on the idia of relationships. The Ja-Net on grid system employs the grid security infrastructure, which is based on X.509 certificates and is included in the Globus Toolkit, to achieve single sign-on and secure access to confidential information. In this paper, we describe the design and implementation of the Ja-Net on grid system, and verify the effectiveness thereof by demonstrating better resource distribution with respect to the conventional master-worker-based task distribution methods.

Realizing external avatar's action control on WWW-based Pseudo-3D space

In the virtual space, as it is common that a user selects an avatar from several avatars provided to represent himself in the space, a number of users may use the same avatar As a result, it becomes hard to distinguish the users by their avatars. However, if each user uses a unique avatar, the relation between a user and an avatar will be one-to-one and the user can customize his own avatar In this research, we propose the Open Avatar Architecture (OAA), which enables users to utilize various virtual spaces using their own avatars. We also implement a prototype system to achieve OAA using pseudo-3D space we have constructed Using this prototype system, it becomes possible to control single avatar in multiple virtual spaces.